pH and Aquaponics
By: Alex (Farm Intern)
What is pH? pH is an abbreviation for “potential of hydrogen” which comes from p standing for “power” and the standard capital H being the element hydrogen. pH is a measure of how acidic or basic/alkaline a solution (could be your water or soil) is. The pH scale is from 0-14 with 7 being neutral 0-7 being acidic and 7-14 being basic. pH is important for plants because it affects nutrient availability, soil bacteria, toxic elements, and more.
In aquaponic systems, maintaining a pH between 5.5 and 7 is the optimal choice for most plants, with some exceptions thriving in more acidic or basic environments. Another factor that is important in growing plants is nitrogen and ammonia levels. These levels can be determined by the bacteria in your farm. The bacteria needed to break down organic matter tends to be the most active between the pH range of 5.5-7. Nitrogen is released by organic matter that is broken down by nitrite-oxidizing and ammonia-oxidizing bacteria in the soil or water. These bacteria regulate the amounts of toxic ammonia and nitrite. The nitrite-oxidizing bacteria breaks down nitrite into nitrate which can be used by plants but can be toxic to fish at high levels.
Maintaining a pH of 5.5-7 will also allow for the most nutrients to be available for your plants. Nitrogen, potassium, and sulfur are not as directly affected by pH as other nutrients can be, but they can be low under extreme conditions. Phosphorus is affected greatly by pH value. When your medium (soil or water) is alkaline or has a pH of 7.5 and above, phosphorus tends to bind with calcium and magnesium to form a less soluble compound that plants may not be able to use. When pH is very acidic phosphorus tends to bind with aluminum and iron to form another less soluble solution. Micronutrients tend to not be as affected by pH but most tend to have larger amounts available in slightly acidic soils, that is a pH of 6.5-6.8.